Numerous applications exist for percutaneous implants, serving as medical and dental prostheses. A fundamental concern associated with the implantation of such devices arises from the natural tendency for the immune system of the host human or other mammal to reject such foreign objects. This occurs primarily through epithelial invasion mechanisms, although the formation of scar tissue, and cellular migration and proliferation around implants, have also contributed to the failure of efforts to develop permanent prostheses.
Exemplary of the prior art that is germane to this technology are the following United States patents:
Mizuguchi et al U.S. Pat. No. 3,556,969 discloses a method in which collagen fibrils are electrodeposited from an aqueous suspension, to produce a shaped article in which the fibrils are randomly arranged.
In accordance with Tregear et al U.S. Pat. No. 3,700,609 a polymer, such as polyethylene or polypropylene, is grafted with an aromatic monomer containing a protein-reactive group to achieve improved compatibility with mammalian body tissue. The resultant structure may be used as a prosthesis to which protein bonding is promoted.
A process for coating synthetic polymers with collagen is described in Okamura et al U.S. Pat. No. 3,808,113, in which a spark plug discharge is used for surface preparation, followed by irradiation of the collagen coating. It is disclosed that medical articles produced exhibit an affinity to living bodies, as well as having other desirable properties.
Pillet U.S. Pat. No. 3,863,344 provides an implantable support for a dental prosthesis, which may be comprised of a stainless steel pin surrounded by a resilient envelope of an organosilicic elastomer. A textile sheet may be adhesively affixed to the surface of the envelope, to render it colonizable by living tissue.
Seiderman U.S. Pat. No. 4,034,750 discloses a bandage adapted for topical application, comprised of a semipermeable collagen membrane which may be linked electrochemically to damaged collagen fibrils of an animal body.
Yannis et al U.S. Pat. No. 4,060,081 provides a membrane including, as one layer, a cross-linked composite of collagen and a mucopolysaccharide and, as a second layer, a silicon resin, an acrylate or methacrylate ester polymer or copolymer, or polyurethane; a reactive prepolymer may be employed to produce the laminate. Subcutaneous implantation, collagen fibrosynthesis at the graft/host tissue interface, and multilayer systems are disclosed, the latter using a silicon elastomer for bonding the composite layer to another material.
Morris U.S. Pat. No. 4,307,472 teaches a technique for increasing the bond strength between a porous polymeric coating, used on a surgical implantation device to accommodate and promote tissue ingrowth, and the underlying structural component, the surface of which may be roughened or otherwise prepared by providing grooves or the like upon it. An interfacial layer is provided between the underlying structural component and the porous coating; for example, nonporous polyethylene may be used for the substrate when porous polyethylene is employed as the outer layer.
A composite polymeric material, consisting of a methacrylic or acrylic ester polymer or copolymer and fibrillar collagen, is provided by Stole et al U.S. Pat. No. 4,427,808. The polymeric material may be applied to a solid support, or it may be reinforced with metallic materials.
Park U.S. Pat. No. 4,491,987 discloses a prosthesis comprised of a metal alloy body, the surface of which may be etched with acid and coated with a methylmethacrylate polymer or copolymer, for improved bonding with bone cement.
DIALOG Information Services, Inc. has published the abstract of an application in the name of Kantrowitz et al, claiming a U.S. priority date of May 31, 1984 and Ser. No. 615,883, which concerns a device to be implanted below the skin and to project outwardly for assembly with a detachable member. The surface of the device is covered with a cultured autologous multilayer fibroblast coating, and the device is implanted in a surgically formed pocket. An advantage disclosed is that epidermal downgrowth along the side of the device is blocked to prevent rejection.
In addition to the patent art, the function of a stable collagen/biomaterial seal in inhibiting epidermal downgrowth is hypothesized in Contemporary Biomaterials (Noyes Publications, Park Ridge, N.J. 1984), beginning at page 506.
Despite the activity in the art indicated by the foregoing references, a demand remains for an implantable percutaneous device for dental use, which is highly effective in providing a support for a dental prosthesis and in avoiding immunological rejection due to epithelial invasion. Accordingly, it is the broad object of the present invention to provide a novel device affording such features and advantages.
It is a related object of the invention to provide a novel method by which such an implantable percutaneous device can be produced, and also to provide a novel method of surgical implantation utilizing such a device.